The people in Halo Wars are new, but the situation is the same: The Covenant is hell-bent on destroying humanity, and they'll do anything to locate, acquire and protect ancient Forerunner technology. It's this obsession that first brought the alien coalition into contact with humanity at Harvest, and Halo Wars gives an interesting early look at how the Covenant view their new adversaries (contemptuously). And love him or hate him, there's even an unpredictable Arbiter on hand to complicate your life and mutter nasty things about humans.

For a real-time strategy game, there's a lot of story to absorb in Halo Wars, and the development team has dropped some tantalizing tidbits into the game's many well-produced cutscenes. Halo Wars co-designer and lead writer Graeme Devine worked closely with Bungie, Microsoft Halo guru (and former Bungie content manager) Frank O'Connor and others to make sure the new game's story fits tightly into the Halo universe. Make no mistake, Pace says, Halo Wars is canon.

Fans of the series will notice nods to series lore sprinkled throughout the game, most of which I'll leave Halo clue hounds to discover on their own. But one of the most obvious examples pops up early on, when the Spirit of Fire leaves Harvest and heads to Arcadia colony to follow up a hunch about where the Covenant may be heading next. But by the time the Spirit emerges from Slipspace above Arcadia, the aliens are already engaging a small group of UNSC warships, including the Pillar of Autumn.

The Pillar was the retrofitted Halcyon-class cruiser that the Master Chief was aboard during the events of Halo: Combat Evolved in 2552, and it met a sad but useful end on the surface of the Halo installation. The Pillar was known for its toughness, which may be why it's one of the only ships in the battle above Arcadia 30 years prior that's not critically damaged in the Covenant attack. But if the Spirit of Fire hadn't jumped in from Harvest to help, would the Pillar have made it out alive? It's an open question, the type Halo is famous for asking.

And Pace assures fans that there are many more questions, and maybe even some answers, to come. Microsoft has big plans for the Halo series, and the story of the Spirit of Fire and her crew is just one part of the franchise's future.

"After being a Halo fan for all these years, there is a sense of vastness you get in Halo Wars, of an entire mysterious history that's existed for thousands of years that shapes and drives this entire universe," Pace says. "Everyone is still the Forerunners' pawns. To this day we have no idea where they are. Why is all this technology still around?"

Part of that mysterious history involves the Flood, the enemy that no one expected in Halo: CE and that every gamer came to hate with a passion over the course of the next two Halo shooters. Well, the Flood is back in Halo Wars, and it's just as annoying as ever. Where the Covenant is clearly alien, the Flood is something wholly other, and it represents a threat not only to humanity and the Covenant but to all sentient life in the galaxy.

But wait, wasn't the Flood a surprise when the Master Chief and the remaining crew of the Pillar of Autumn located it on the surface of the Halo installation in the first game? How is that Forge, Anders, Cutter and crew are tangling with them 20 years earlier? Good question, and one of the many you'll have to answer for yourself when you play the game.

Like its predecessors, the newest entry in the Halo saga offers as many openings as it does closures. The Master Chief would have been 20 years old during the events of Halo Wars. What is he up to while Cutter, Forge and friends are tangling with the Covenant? How is Prof. Anders able to operate Forerunner technology in ways the aliens cannot? And what ever happened to Jonesy the cat?

At the end of Halo 3, the Master Chief and Cortana spin lazily in space, their fates unknown. Halo Wars doesn't aim to erase that melancholy image. Instead it provides a historical counterweight to the nebulous future of mankind's greatest hero.

We'll be continuing our week-long coverage of Halo Wars tomorrow with a detailed look at the units of Halo Wars and how they compare to their counterparts in the first three games in the series. In a video special, we'll show you how each of the franchise's most prominent vehicles and troops have appeared through the years. You'll also get an up-close look at the new vehicles Ensemble's RTS introduces to the Halo Universe, including the Cyclops building killer and the Vulture uber-aircraft.